It is known to provide structural fibre-reinforced hot-melt epoxy composite materials. Inorganic fillers are commonly added to epoxy resin systems to modify properties, for example to modify the thermal and mechanical performance, to impart fire-retardant properties, to customise the rheological and handling properties, to increase ultraviolet (UV) radiation stability, and to provide weathering resistance. Traditionally, these fillers are dispersed homogeneously throughout the resin matrix. Many improvements in properties do not require such homogeneous dispersion and so this may result in a material which is thus either over-engineered for the application or, conversely, reduced in one or more other properties.
EP-A-0124403 discloses a collar comprising a central body of resin containing inert mineral fillers and outer layers of fibre reinforcement, the outer fibre layers preventing the passage of the mineral fillers outwardly from the central body.
WO-A-02/046276 discloses hybrid composite articles in which polymer particles are distributed evenly throughout a strand and substantially fill the gaps between individual fibres. The polymer particles are significantly smaller than the fibre diameter so that there is a homogeneous dispersion of the polymer particles throughout the resin matrix.
Epoxy resin matrices are inherently not fire-retardant. It is known that a hot-melt epoxy resin system can, however, achieve increased fire-retardant properties through the incorporation of inorganic fillers. Fire standards vary significantly depending on the application and country in which a fire-retardant material is to be used. However, in general, several common properties are measured as part of a fire-standard. These include: heat release, smoke density and toxicity, burn rate and time to extinguish.